Gadolinite-(Ce) & (Y)

This article has been prepared for the Mindat Best Minerals project. The aim of this project is to present information on important localities and specimens for each mineral specie. As new finds are made and new knowledge is made available the individual articles will be revised to include this information. Readers are encouraged to contribute by posting a response in this thread. All revisions will be stored, thus ensuring traceability and availability of previously included information. A complete list of articles can be found in the list of finished Best Minerals articles.. To cite this version: Revheim, O.,(2015): Gadolinite-(Y) and -(Ce). revision 2.0. Mindat Best Minerals Project, article "mesg-73-148537". . Please be advised that the photos cannot be used without the consent of the copyright holder

Monoclinic

Gadolinite is a rare mineral first described from the famous Ytterby pegmatite outside Stockholm, Sweden. There are two gadolinite minerals, gadolinite-(Y) and gadolinite-(Ce); the latter being less common with only 35 localities registered on Mindat and 145 localities for gadolinite-(Y). The gadolinite minerals are structurally similar to other minerals generally considered as the “gadolinite-datolite” group. Individual minerals of this group can be difficult to distinguish, and intermediate compositions are not uncommon.

The first description of what now is gadolinite-(Y) was given by Gejer (1787) based on an odd piece of black, coal-like rock found by the Swedish army lieutenant, Karl Axel Arrhenius. Geijer describes its visual appearance (looks like asphalt or coal) and associated minerals, as well as reactions with acids and under the blowpipe (it swells like a zeolite). He proposed that it might be an ore of wolfram, which was discovered and described six years earlier.

Later, the chemist Johan Gadolin of the University of Åbo at Turku, Finland investigated the new mineral and announced in 1794 that the odd black rock contained 38wt percent of a new "earth", which he named Yttria, now Yttrium. He had isolated yttrium oxide. The black rock was, of course, an unknown mineral and it was later named gadolinite. Gadolinite was subject to thorough research by scientists in the 19th century, and is one of the mineral species that had the greatest influence on the development of mineralogy and chemistry in this period. After Gadolin's discovery of yttrium, it was found that the oxide of this new element had different properties when extracted from different sources, indicating that it contained impurities from other elements. Carl Gustav Mosander's successful isolation of Erbium and Terbium (both named after Ytterby) in 1843 sparked interest among chemists and mineralogists in this group of elements (Rare Earth Elements or Lanthanides). The British chemist William Crookes summarized the excitement of the time:

" The Rare Earth Elements perplex us in our research, baffle us in our speculations and haunt us in our very dreams. They stretch like an unknown sea before us, mocking, mystifying and murmuring strange revelations and possibilities".

At the center of all this excitement was the ugly, black mineral gadolinite. A total of 7 (Emsley 2001) elements were first extracted and identified from gadolinite, namely Terbium, Erbium, Ytterbium, Lutetium, Holmium, Thulium and Dysprosium. Properties like metamictization (in which radioactivity damages the internal structure of minerals over time, so they become amorphous) and that heat may restore this structure were also first described from gadolinite.

In the USA, gadolinite was found in the great Baringer Hill pegmatite, where a more practical use was found for the new element Yttrium. Thomas Alva Edison found that yttrium oxide was a useful "glower" in electrical lamps. In 1903, he sold the rights of the yttrium lamp to the German chemist Walther Nernst, who gave his name to the "nernstlamp".

Gadolinite can be found in three very distinct environments. The largest crystals, generally metamict gadolinite-(Y), are found in granite pegmatites, where crystals and crystal groups of considerable size (up to 500 kg) are embedded in feldspar. Gadolinite-(Ce) may also be found in pegmatites, but is associated with alkaline pegmatites. These crystals are normally black and metamict amorphous, but can nevertheless be found in complex and beautiful crystals. 33 different crystal shapes have been described from Hidra, Norway alone, and Goldschmidt has drawn up 30.

Gadolinite can also occur in miarolitic cavities in various granites, where it can be partly embedded in small pegmatites and partly formed in cavities by hydrothermal solutions in a wide range of conditions. Gadolinite may also be found as a hydrothermal mineral in alpine clefts. In these environments, the crystals are much smaller, rarely more than 1 cm, but may be non-metamict and show a wide variety of habits and colors. These crystals are generally chemically complex, with intermediate compositions and zoned crystals. In alpine occurrences particularly, a rather large variation in chemical composition can be observed, with composition grading towards hingganite (Fe-deficient) or datolite (Ca and B-enriched).

Most specimens displayed in museums are from Norway, Sweden or Barringer Hill, Texas. In particular, those museums acquiring high-end specimens in the 19th and early 20th centuries have very fine gadolinite specimens; these include the British Museum, Smithsonian, Fersman, Ecole du Mines and several German and Scandinavian museums.

The Municipal Quarry locality is a long-abandoned quarry in a granitic gneiss with crossing aplite and pegmatite veins. The mineralization occurs in alpine-type clefts in the rock, and small (micros) but well developed gadolinite-(Y) crystals have been found.

Slama (2009) gives the following account on these localities: "The Municipial quarry has only one cleft with Gadolinite in the left corner of the quarry. Some people have found gadolinite in the last years, I have found my only Gadolinite in 2007. Interesting at the Municipial quarry is that the gadolinite xls are mostly well terminated and not metamict. Most gadolinite xls are associated with muscovite, chlorite, well terminated aeschynite-(Y) and titanite, sometimes with rutile or brookite.

A similar but better gadolinite locality is the "Moos", which is located about 150 m behind the Municipal Quarry. At this locality, gadolinite-(Y) is quite common and still can be found today. From this location the largest Austrian gadolinite is known - a perfect crystal of about 1.5cm that was found by Roland Winkler. The locality is small, but even today gadolinite can be found. The last found I know is only one week ago."

Demartin et al. (1993) provide microprobe data on the gadolinite from both of these localities and confirm the identification as gadolinite-(Y).

Schrammacher Mountain is located in the western part of the Tauern window in the Alps. The Tauern window is an exhumed part of crustal rocks that are highly metamorphosed (greenschist to amphibolite facies) and have a complex history of various events. The mineralization occurs in alpine clefts, which opened up during the late stages of the Alpine orogenesis and provided a suitable space for deposition of hydrothermal minerals. The host rocks for the clefts at this locality are metamorphosed quartz porphyries enclosed in a conglomerate gneiss.

Holtzer and Stumpfl (1980) suggest that these waters were largely sodium chloride solutions, which have been heated up at comparatively shallow depth, possibly in zones of increased heat flow linked to plate tectonic processes. These hydrous solutions have reacted with the country rock, resulting in selective leaching for the deposition of a large variety of minerals throughout the Alps.

Gadolinite-(Y) found in alpine clefts in the Schrammacher area are typical of this type of occurance, in that the gadolinites are small (2-3 mm), bottle green, transparent and non-metamict. The gadolinite-(Y) occurs with genthelvine and other rare minerals, and the identification of gadolinite-Y is supported by SEM/EDS.

A gadolinite/datolite group mineral has been identified via SEM/EDS and XRD. This was part of a small find in sanidinite ejecta. The "gadolinite" occurs as mm-sized, brilliantly green and transparent crystals in small vugs in the sanidinite. It was associated with zircon, green pyroxene, nepheline, "cancrinite", baddeleyite, "pyrochlore", britholite-(Ce), "hellandite", magnetite, fluorite, "sodalite" and biotite. The exact species has not been determined.

Small (rarely larger than 3 mm) gadolinite-(Y) crystals from the quarries near Cuasso al Monte occur in miarolitic cavities associated with a leucogranitic pluton (275 ± 8 Ma), which intruded a thick sequence of Permian volcanic rocks. The leucogranite is mainly composed of aplitic microgranite and miarolitic granite having a granophyric texture. Aplitic-pegmatitic pods and veins, locally related to large miarolitic cavities, are widespread.

Miarolitic cavities (typically smaller than 1 cm) are abundant throughout the entire outcrop of the granophyric granite. Larger cavities (up to 1 or 2 m) have a characteristic vertically elongated shape and are commonly rooted in an aplitic-pegmatitic pod or vein. Most of these larger cavities were interconnected during their crystallization. In many cases, carbonates, sulfates, and/or fluorite have filled the cavities completely during the latest stages of fluid circulation.

Pezzotta et al. (1999) have studied the gadolinites from Cuasso al Monte and distinguish between gray-brown crystals occurring in “primitive” cavities and strongly zoned crystals with a dark core and a translucent white rim in “evolved” environments (i.e. exposed to extensive hydrothermal action). The gray-brown crystals consist of relatively uniform Nd-rich gadolinite-(Y), whereas crystals with a white rim contain a core with similar composition as the gray-brown crystals, a Y-rich intermediate zone, and a hingganite-(Y) rim.

The pink granite of Baveno is a medium-grained granite showing intense, late post-magmatic alteration due to an abundance of fluids in both pneumatolitic and hydrothermal stages. Miarolitic cavities occur isolated in the pink facies of the granite, in pegmatitic veins (where they have irregular shapes), and in aplitic-pegmatitic dikes. These dikes contain granophyric portions characterized by several small cavities in the aplitic units, and large, vertically elongated, cavities in the pegmatitic units. These cavities range from 1 cm up to 2-3 m in diameter. All the cavities developed as isolated systems and, in some cases, the largest ones are partially collapsed.

The paragenesis is typical of NYF-pegmatites and developed under magmatic, pneumatolitic and hydrothermal conditions. Among the Y-REE minerals, only gadolinite group minerals are present from the earliest magmatic stage to the latest low-temperature hydrothermal event. Gadolinite group minerals are therefore found as primary high temperature minerals in the primary pegmatite dikes as well as with low temperature, hydrothermal minerals in the cavities. The gadolinite group crystals are rarely larger than 1 cm, but crystals up to at least 2 cm are known.

Both the physical appearance and chemical composition of the gadolinite group minerals change as a function of temperature and environment. In the primary pegmatite, the gadolinites are black and near the gadolinite-(Y) end member in composition. In the miarolitic cavities, the crystals are zoned. The core is dark (black) with a gadolinite-(Y) composition and, towards the rim, the color becomes lighter (white) with increasing hingganite-(Y) and datolite components. In zeolite associations, the gadolinite group mineral can be datolite.

Gadolinite-(Y) is found as green transparent crystals in alpine clefts in gneiss at the Beura quarries. DeMartin et al.(1993) have analyzed gadolinite from here, confirming the gadolinite-(Y) identification. The mode of occurrence is similar to the Austrian localities.

Fosso Bovalico in one of many pegmatite dikes in the viciniy of San Piero in Campo on the island of Elba. All these pegmatites are closely linked to the history of the Monte Capanne pluton, a 6.7–6.9 Ma monzogranite. The pegmatite and aplite veins are found near the margin of the pluton, into the surrounding contact-metamorphic aureole.

Well crystallized minerals occur in miarolitic cavities in the pegmatites, and their sizes range from 1 cm3 and upwards. These pegmatites are much studied, and the mineralogy within the cavities changes with temperature and position in the pegmatites. Aurisicchio et al. (2002) distinguish between “primitive pockets” near the core of the pegmatite, and “evolved pockets” near the margins of the dikes. Lucci and Pucci (2012) have identified mineral assemblages of high (450-550o C), medium (200-450o C) and low (150-200o C) temperatures.

Gadolinite-(Y) is a very rare mineral in these pegmatites and listed only from the Fosso Bovalico pegmatite, where it occurs as dark bottle-green crystals no more than a few mm in size.

The Hidra pegmatites are classic localities for REE minerals, and has produced some of the largest and best crystals of gadolinite-(Y) that have ever been found. Due to its coastal proximity, the island of Hidra was an early Scandinavian producer of feldspar and quartz; production started early in the 19th century and continued until 1919. Today, all of the quarries are water filled, and the dumps are either removed or overgrown. Hidra soon became a major source of gadolinite for research, together with and following the Ytterby pegmatite, when this no longer was a source for gadolinite-(Y). Gadolinite from Hidra is represented in several museums across Europe, and the university of Stockholm holds 35 gadolinite-(Y) samples from Hidra in their collections (Brotzen 1959). The best crystals can be admired in the display at the Geological Museum in Bergen, as in the uppermost photo shown here.

There are at least 10 different pegmatites (maximum 6 m wide and 100 m long) on Hidra that contained gadolinite-(Y) and, in particular, Urstad and Igletjern supplied large crystals. Adamson (1942) gives an account of the occurrence: " Gadolinite is found in all the much worked quarries, but in varying amounts. It occurs partly as beautiful crystals of about 1 cm magnitude or smaller, partly as about 5 cm large crystals, then mostly with biotite, partly as enormous crystals up to 40 cm length. It is always found altered into a metamict state. The faces sometimes have a yellow-white covering of tengerite. Gadolinite has been observed in quartz, microcline, oligioclase, biotite and muscovite. It is clear that the formation of gadolinite extended over a long period. the small, beautifully crystallized forms of rich gadolinites are obviously formed first. The crystals that grow upon biotite, and consequently are younger than biotite, are poor in forms and are generally irregularly developed. The big gadolinites sometimes show a contemporary crystallization with mica and feldspar. "

The pegmatites are linked to granitic intrusions from the Sveconorwegian orogeny (900-1100 Ma).

The pegmatites in the Evje/Iveland district are enclosed in a 15x30 km metagabbroic complex, and appear to have been emplaced along pre-existing zones of weakness. The pegmatites are enriched in REE elements and are believed to be formed late (~850 MA) in the evolution of the Sveco-Norwegian orogeny at a relatively high temperature (~600o C). Their composition indicates a crustal origin.

The first quarries in the pegmatites were opened as a source for quartz, to be used as a flux to ease the melting of the pyrrhotite/pentlandite ore at the Flåt Nikkelverk from 1884. Following the reduction in logistics cost upon the opening of the Setesdalen railroad in1896, the production of feldspar became commercially attractive. It did not take long before the occurrence of rare minerals, such as gadolinite-(Y), became apparent, and Brøgger was there in 1906, describing several of the minerals. In addition to quartz and feldspar, there has also been commercial production of other minerals, such as muscovite, beryl, thortveitite and gadolinite-(Y). In total, several tons of gadolinite-(Y) have been mined from pegmaties in this area.

Gadolinite was one of the profitable by-products from the feldspar production, and decent records of the production have been kept. Good crystals of gadolinite have been found in several quarries in the area, and these pegmatites are the source of the largest and finest gadolinite-(Y) crytals ever found. The largest known individual crystal weighed 500 kg, and stood out in the pegmatite like “a small, squatting man”. Crystals exceeding 100 kg are known from several of the quarries. Gadolinite from here shows a remarkably complex crystal development, and numerous crystal shapes. Most of the larger (> 1 in.) specimens available on the market today are from the Evje/Iveland district and are often older specimens, although good finds are still being made. Old specimens are often labeled "Sætersdalen", "Setesdalen" or similar.

This is a general geographical area in the northern part of the Iveland municipality. Older specimens labeled "Frikstad", "Iveland" or "Setesdal" would likely have their origin in one of the quarries in this area, although it is virtually impossible to determine which one. I have chosen three of the quarries for further description below.

The Slobrekka pegmatite was considered to contain the largest volumes of gadolinite-(Y) of the quarries in the Evje/Iveland area. Bjørlykke (1937) calculated that the Slobrekka pegmatite contained approximately 0.013 wt% gadolinite. There are no official records of the total quantities produced, but Øyna (2008) describes several finds of single crystals and shipments of gadolinite in the multiple-100 kg range, and total production can be measured in tons. The largest gadolinite crystal has been found here (+/- 500 kg). In 2003 and the following years, several black, shiny and complex crystals were found. The largest were about 10 cm.

The Hundholmen pegmatite was mined from 1906 to about 1970 for feldspar, along with some quartz and fluorite. Today, the mine itself is abandoned and opened towards the sea, acting as a harbor for sailboats. The dumps are still accessible, and are known to host a number of very rare minerals, some of them world-class quality. It is one of the largest and most mineral rich of several granite pegmatites in the Tysfjord area of Northern Norway.

Gadolinite-(Y) has been found in some of the pegmatites in the border zone of large masses of yttrian fluorite and as grains embedded in the yttrian fluorite. Good crystals to several mm, rarely up to 1.5 cm, have been found. The gadolinite-(Y) from Hundholmen is bottle-green and non-metamict, which is unusual for gadolinites from REE-pegmatites

The 3x5 km Zagi mountain rises only 175 m above the valley. It is part of a granite ridge, protruding in the landscape above the more easily eroded metamorphic rocks on both sides. It consists of an alkaline granite containing both aegirine and riebeckite, in addition to other dark accessory minerals. The granite belongs to the Warsak igneous complex, and its petrology is described by Ahmad et al. (1969) and Tahirkheli et al. (1990). It is noteworthy that both the granite and the surrounding rocks contain many quartz and calcite veins (but very rarely pegmatites). The veins are deposited along fractures in the granite, and some of the quartz veins are several feet thick.

Tahirkheli et al. (1990) provide chemical analyses of these rocks, including trace element analyses, showing around 500 ppm REE and roughly from 1000-2500 ppm Y. Khan (2009) suggests a late stage fractionation of the REE of the alkaline magmas prior to their being partitioned into hydrothermal fluids. Several REE and Y-bearing minerals are deposited along fractures and veins or in vugs. Oddoba (2015) observed that many of the best crystals are found in heavily weathered rock, either as single crystals or with only minor matrix attached.

Many of the REE minerals show good crystal shapes, and the bastnaesite-(Ce) and parasite-(Ce) are certainly among the best ever found. Gadolinite can also be found in this association, although not commonly, and apparently rarely in crystals exceeding 1 cm. The crystals are brown and non-metamict. The chemical composition may be variable, as gadolinite-(Ce), gadolinite-(Y) and hingganite-(Y) are listed in Mindat. However, it is uncertain whether there is sufficient material available to perform a thorough study on the chemistry of the gadolinite group members from this locality.

There are two gadolinite-bearing pegmatites on the Kårarvet farm, termed the "old" and the "new" workings. The old mine was discovered in 1815 by Jöns Jacob Berzelius, Johan Gottlieb Gahn and Nils Nordenskiöld, while the new mine was found by Adolf Erik Nordenskiöld in the 1850s. The main product was quartz, but also the occurrence of REE and Y minerals were of significant interest. Today these workings are nature reserves, based on their key position in the older mineralogical and chemical research and are thus of significant historical scientific value.

Gadolinite was found in elongated wedge-shaped pieces without obvious crystal shape, often enclosed in a thick, rusty crust of alteration products and sometimes completely altered. Gadolinite could, as a rarity, be found in well developed crystals like the one pictured. Gadolinite occurred in a coarse grained quartz/microcline/plagioclase/muscovite pegmatite with garnet and other Y/REE minerals.

The Ytterby pegmatite was the first pegmatite opened for production of feldspar in Sweden. Feldspar production started about 1794, but it is possible that quartz production started more than 100 years earlier. Production ceased in 1933, but even today, more than 75 years after end of operation, this mine is an icon for everyone interested in REE minerals and elements.

Ytterby is the type locality for gadolinite, yttrotantalite and tengerite.

The pegmatite is almost vertical with a ”pinch and swell” structure. The 5-6 expanding “swell” areas could be followed down to approximately 160 m below the surface. The pegmatites were worked for quartz and feldspar. The rare minerals, REE-Ta-Nb-Ti oxides, REE phophates as well as carbonates and silicates were more abundant in the upper parts of the pegmatite, to about 50-60 m below surface level, with the uppermost 25 m being the richest.

The Ta/Nb fraction was higher in the upper portion of the pegmatite than further down. The Ta-dominant oxides yttrotantalite and formanite were more common near the surface, whereas fergusonite became more common toward the deeper parts of the mine in the middle of the 19th century.

Gadolinite occurs in feldspar with biotite or muscovite, often associated with the Ta-oxides. The crystals vary from approximately pea size up to large fist size. It was difficult to free undamaged crystals but, when successful, specimens of very high quality was the result. The gadolinite paragenesis is frequently brecciated and pseudomorphosed to xenotime-rich nodules. Gadolinite was found with biotite that had often restricted the development of the gadolinite crystals. It was also found embedded in microcline, most frequently with poorly developed crystals, but quite often as perfectly developed crystals. A total of 14 different crystal shapes are described. According to Petersen (1890), gadolinite was quite frequent in the upper parts of the mine, or in his own words: "gadoliniten.....påtraffats i mycket riklig mangd".

This locality is a little visited pegmatite that was worked for fluorite in the 1960s - 70s, but is now abandoned. During active times, gadolinite was not too rare. Karthasov (2015) describes the occurence of gadolinite as “an early stage mineral, and I suppose, that the main part is preserved in situ in unopened parts of border zone of the pegmatite. Only its central parts were mined for cavities with quartz and fluorite.”

Gadolinite-(Y)UK, Scotland, North West Highlands (Inverness-shire), Isle of Skye, Luib, Eas a Bradain

Gadolinite-(Y) has been found as crystals in miarolitic cavities in some of the small epigranitic intrusions in the Cuillin complex. It is a rare species from the granites, so far found only in the Loch Ainort granite. All the crystals of gadolinite-(Y) show some alteration and etching, sometimes with later crystals of allanite-(Ce) grown on them. The gadolinite-(Y) crystals are bladed and to 1.5 mm long, occasionally in sub-parallel groups with a grey-green to slighly translucent yellow color.

Gadolinite has been found in several places in Colorado and has been produced commercially as a source of yttrium for the Nernst gas-light mantle in the early 20th century. With the increased demand for REE minerals in the 1950s and onward, studies and sporadic mining have been undertaken for Y-bearing minerals such as gadolinite. However, the occurrences are small, irregular and diffuse, and are without commercial potential as an ore.

Gadolinite masses and crystals have been found in several pegmatites; in particular, the Clear Creek and South Platte pegmatite districts. Some 15 tons of gadolinite-xenotime-monazite ore was obtained from the Snowflake deposit and a “carload” of gadolinite-rich ore was produced from the White Cloud deposit. (Simmons and Heindrich,1980).

The crystals are generally not as attractive as the ones from Scandinavia and Baringer Hill, in that they are generally coarser in shape and often altered. Atkinson (1910) was the first to acknowledge that gadolinite found in Colorado was richer in Ce than gadolinite found in Texas, and Eckel (1961) introduced the varietal name "cergadolinite". Over time, this variety has been translated into the mineral gadolinite-(Ce), although no analyses showing a gadolinite with Ce>Y has been published. Simmons and Heindrich (1980) have performed “qualitative electron microprobe analysis (that) indicates that in addition to yttrium-group elements, cerium-group elements also are present. Thus this material may actually be a cergadolinite (gadolinite-(Ce), Levinson 1966)”, but they published no data and considered gadolinite as a Y-silicate and Y-ore.

In the White Cloud pegmatite and other pegmatites in the South Platte pegmatite district, gadolinite occurs as long, slender prismatic crystals with pyramidal terminations and diamond-shaped cross sections. Crystals are as much as two inches long and are usually embedded in fluorite and yttrofluorite in association with allanite. Most crystals are metamict or highly altered by subsequent fluocarbonate mineralization, and X-ray patterns show only alteration products.

The Roscoe Beryl Mine has produced perhaps the best gadolinite specimens in Colorado. Ercit (1961) reports that the crystals are uncommonly well developed; the largest partial crystal is 11 cm in diameter, in addition to masses of gadolinite weighing as much as 10 pounds. Here, gadolinite is embedded in feldspar (microcline and albite) and was found associated with xenotime, fergusonite, uraninite, beryl, and a little molybdenite .

Baringer Hill is the most famous NYF pegmatite in North America. It was discovered in July 1886 by John J. Baringer and, between1889 and 1907, it was vigorously promoted by William E. Hidden. A few hundred kilograms of material, predominantly fergusonite-(Y) and gadolinite-(Y), were mined each winter from 1902-03 until 1906-07 as a source of "yttria" for glower strips (i.e.,filaments) for Nernst lamps. The pegmatite was flooded by the artificial Lake Buchanan in 1937, and is no longer accessible.

The Baringer Hill pegmatite is an asymmetrical, zoned, metaluminous pegmatite about 75 m long by 30 m wide. Baringer Hill lies on the east side of the Llano Uplift, which exposes a Grenvillian terrane of gneisses and schists intruded by a suite of post-orogenic granites. The Baringer Hill pegmatite intrudes the Lone Creek pluton of the Town Mountain granite and is the largest NYF pegmatite here. It has a graphic granite wall-zone < 2 m thick, a quartz-perthite core, and a red albite + quartz + microcline unit, which is the source of the REE minerals and has been interpreted as a replacement.

Gadolinite-(Y) forms prismatic crystals terminated by a pinacoid or a pyramid. Crystals and masses may be quite large. One 73-pound group of double crystals collected in March 1903 was considered by Niven to be the greatest group of crystals, and several crystals in the 20 cm+ range are kept in American and European museums. Gadolinite-(Y) often has a brick red or yellow alteration coating in which tengerite-(Y) has been identified.

The Golden Horn Batholith is a highly evolved alkaline (sodium-rich) granite that hosts a suite of rare minerals in small pegmatites and miarolitic cavities. Gadolinite-(Ce) is found as small (mm size) brownish crystals in miarolitic cavities in the rock.

According to Kroti (2009), gadolinite-(Ce) “was found to be metamict, and required gradual recrystallization by annealing for forty-eight hours at 700˚ C, before a distinct diffraction pattern could be obtained. Accomplished by John Attard in December 2008, the pattern matched gadolinite-(Ce) type material from the Bjørkehagen pegmatite near Buer, Norway, reported by Segalstad and Larsen (1978).

In many samples, the outermost zones or encrustations are yttrium-dominant, (in 8-fold coordination), but within the inner cores Ce dominates Y by a large margin. I do not yet know how consistent this observation will prove to be, but was was so for thirty crystals examined.”

Olav,I would like to upload an image of Gadolinite to Mindat, but am not sure what locality to put it under. The specimen is one I took a picture of in 1975 in the British Museum and the label said Saetersdalen, Norway. Dalen appears to be a common ending for localities there, but I can find nothing with Sateters in the front. Perhaps you can help with this.

that because its seter, or sometimes sæter, saeter or other, and if you look at the first entry, you can see that this is probably one of the iveland or evje localities. Exactly which one maybe someone else knows.

The specimen from British museum is from one of the quarries in the Evje/Iveland area. The name Dalen means Valley. The Setesdalen valley is a 200+km long valley, but it is only some of the granite pegmatites in the Evje/Iveland area that carries gadolinite. Which one of the quarries is impossible to know.

I think that this must be one of the early finds early 1900-hundred, and that it originally probably was labeled Nedre Setesdalen ( Lower Setesdal valley) and that the administrative borders and names has changed since then. Therefore the locality label seems a bit haphazard today.

Nice start on a Gadolinite article.Just a corrections: The Gadolinite-Y Xl from Hundholmen in Tysfjord is 1,5 cm as stated in the text of the photo in Mindat.As to the text for Hundholmen you might write:"The Hundholmen pegmatite is one of the largest and most mineral rich of a number of granite pegmatites in the Tysfjord area of Northern Norway. The pegmatites are rich in REE-minerals. Gadolinite-Y has been found in some of the pegmatites mainly in the border zone of large masses of yttrian Fluorite and as grains embedded in the yttrian fluorite.Good crystals to several mm have also been found and more rarely at the Hundholmen pegmatite larger and well formed crystals to about 1,5 cm are known. The Gadolinite-Y from Hundholmen is bottle-green and non-metamict which is unusual for Gadolinites from REE-pegmatites."

Some of the largest and best crystals of Gadolinite-Y ever found come from the pegmatites of Hidra and large groups can be admired in the display of the Geological museum in Bergen. I hope you will get some pictures of those.

I have found a few documents in the NGU and SGU library databases that they have promised to send me. I believe that there will be some useful information in these documents. I find writing these articles very educating, but unfortunately, it takes some time.

Hi Olav,the Municipial quarry in Böckstein/Austria is long time abandoned and there is only one cleft with Gadolite in the left corner of the quarry. Some people have found Gadolinite in the last years, I have found my only Gadolinite in 2007. Intersting at the Municipial quarry is that the Gadolinite xls are mostly well terminated and not metamict. Most Gadolionite xls are associated with Muskovite, Chlorite, well terminated Aeschynite-(Y) and Titanite, sometimes with Rutile or Brookite. In your article I`m missing another important localiyt where Gadolinite have been found, it is the location called "Moos" which is located about 150m behind the Municipial quarry. At this location Gadolinite-(Y) is quite common and can also be found today. From this location the largest Austrian Gadolinite is known, it is a perfect xtl with about 1,5cm and has been found by Roland Winkler! However the location is really small even today Gadolinite can be found. The last found I know is only one week ago.

I probably have most of the publications you may be looking for concerning the Norwegian pegmatites with Gadolinite-Y and have consulted a few of them.

Gadolinite-Y in rough crystals to about 10 cm - sometimes covered by Muscovite - are not uncommon in the Li-bearing pegmatites in Tørdal (Høydalen) in Telemark. Sharp crystals to a few cm are known from a pegmatite in Fyrrisdal. Gadolinite is uncommon in the many pegmatites along the coast from Bamble to Kristiansand and I have seen no good crystals. A brownish, Ca-rich Gadolinite- Y occur at the Karlstadgangen pegmatite but only poorly crystalized. Gadolinite is known from pegmatites inland from Arendal ( i.e. at Froland). The pegmatites on the island of Hidra in Vest-Agder was worked in the 19th century and some of them produced large and spectacular crystals of Gadolinite to more than 30 cm (especially Urstad and Igletjern).

Thank you very much for the input on the Austrian locations. I have grouped the Municipality quarry and the Moos location into one entry. I hope that is OK with you? Do you, or anyone else, have the opportunity to get a photo of the 1,5cm crystal from Moos? That would be awesome and would improve the article a lot.

Knut, Your knowledge and experience is invaluable.

Also Aksel Österlöf has reminded me of the gadolinites of the Routevarre pegmatite. Ha has already sent me an extensive paper on this pegmatite and I am surely to blame for not remembering what I've read just a few weeks ago. I'll include it. I don't have time right now.

For the two articles I have wrote so far I am just throwing myself into it, and I am totally dependant on the knowledge and experience of you all, both for filling in all my blanks, but also to provide QC on the stuff that I write.

Olav, Each caption should start with the name of the species in the image. Also make sure your localities above the images are in reverse locality order. When you take care of this, Ill come in and work a little more on the formatting to bring it more in line with our current standards.

Hi Olav, the geologic description is correct, respect the gadolinite of the Schrammacher Mt.In the discussion I add another place that is the Vizze Pass and it is near to the preceding one where I have found the gadolinite in small but well formed crystals of quality it gemmates.Unfortunately also in this place as in that preceding they are very rare, but at times looking for with some fortune they are found.The rock is always metamorphic and more precisely an quartzporphyr in a conglomerate gneiss absorbed.Very interesting the fact that is the same fissure mineralized where the genthelvite and others rare mineral is found.Ciao.http://www.mindat.org/photo-158990.htmlhttp://www.mindat.org/photo-158242.html

Hi Olav,for me it is ok when you describe the Municipial quarry and Moos together. The large Gadolinite was found by Roland Winkler and has been published in the Lapis Magazine years ago (Lapis Magazine November 2003). I don`t hae the elder Magazines but I try to get it.

Thanks for your fantastic input for this article. I will not have the time to update it the next week or so I think, but the upcoming work are:

- update the Moos location with the article reference and where the big one is located- include the Vizze pass and the White cloud pegmatite as new location.- include http://www.mindat.org/loc-4130.html, with this: http://www.mindat.org/photo-203028.html- Expand the description of the Ytterby and Hidra locations based additional information.- include photo(s) from the Hidra pegmatites

If possible, include more information on the scientific work based on gadolinite from Ytterby and Hidra.

A special thanks to Jim for introducing an American locality The US has 2 pages of listed localities. Some of them must have produced quality specimens.

Again, Thank you so much for your amazing and great input. I am learning so much from this work. Thanks again.

Barringer Hill produced some large crystalline masses. About 40 years ago, I recollect that a rock shop in the area had a fist sized crystal of gadolinite. He didn't really seem to want to get rid of it as he had a $3-5000 price tag on the black ugly crystal.

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